Circuit breaker



July 14, 1936. L, s WALLE 2,047,842

CIRCUIT` BREAKER Filed Apri1`25, .1933

'A2 sheets-sheet 1 Im/efor' v Ludwig .5.. Walle by,

His Afforvneg July 14, 1936.k

L. s. wA-ITLE v CIRCUIT BREAKER Filed April 25, 1955 2 sheets-sheet' 2,l v

Inventor:

ig 5. Walle,-k

ww r `oA fm A. w d H u .L

Jay'

STATES VLlulv'rig Si Walletv Lansdowne, Pa., a'ssignor to General`Electric Campani a corporation-of .New York v.

Y Application April z5. 193s. Aserian Na 667,856 a4013111.15'(cLzo-'lleo'A n j -My invention relates to circuit breakers,more particularly to circuit breakersof the type known *jasbranch-circuitclrcuit breakers which provide the protective featurescharacteristic of a fuse aswell as the additional advantages of.amanually v 1, operated switch, ,and'has for any object the profvisionoi' a simple, reliable and inexpensive circuit breakerof this-character.lo; f-'; Heretofore, branchy circuit breakers have been -provided with athermal release arranged to trip "time circuit breakerliponltheoccurrence of4 an overload. and with a. manually operablehandleV Fior opening .and closing the circuit independently ofk thethermal release.` However. muchl isffyet to vbedesired in such circuit'breakers [hitherto proposed to replace fuses because-oi ofthe, factthat the arc has been extinguished by ymeans of magnetic 4blowouts andthe .like

withresulting llame and 'arc gases. Inas'much' as branch circuitbreakers-as applied to panel? y boards ion the protection o flighting/circuits,

are called upon yto interr.upt'currentsoi.' :very

considerable magnitude,v as high as 5,000y amperes orsmore, 'when thebreaker carries out the .short acircuit protective 'functions oi afuse,` git'will rbel'appar'ent that a considerable 'quantity of arcgases "are-generatednand that 1 the flame voi-the is quite appreciable;thesetwo features be# T ingfundesirable for circuit breakers forhousevrho'ld Furthermore; since the fuses which v have hithertobeenusedaccomplish thisy inter-- built up the resistance becomes so greatthat the arc can no longer exist, and it is extinguished.

For' a more complete understanding of my ing vention, reference shouldnow be hadto the accompanying -drawings wherein I Vhave showndiagrammatically, in Fig. 1 aside view partly in section of a circuitbreaker embodying my invention; Fig. 2 shdws the parts of the circuitbreaker o1' Fig. l'just before the-contacts are closed, while Figs. 3,4, 5and 6 illustrate an improved form o f a' circuit breaker embodyingmy invention.-

, Referring now to Fig. 1', I have shown my invention inv one formasapplied to a branch-circuit-breaker suitable' for lighting circuitsindicated `by the conductors Illv and I I. The circuit 15 breaker,mounted on an insulating base I2,v comprises-a frame' I3 forthejoperating mechanism, 'a b imetallic thermal element .Il and an arcin-n i terrupter I5. 'I he frame IJjhas anupturned end I8 from whichispivotallysupported at I1 an 201 l 22 provided in a pair Vof parallelL-shaped links 26 25 y l between which the, member .I lmoves. One pairof adjacent ends 29 of the parallel links 26 are p'ivotally secured at30 to the movable,'conta'ctinemberv `II of the arc interrupter I5.Iheother ends 3l of 'the links ze areprovided witnprojecuons u which soI are engagediby adjacentvends of a pair of springs l ",ruptlon-iof -thecircuit withoutspurts of llamen I1 which embrace the -links 20. Theother ends jand'withoutfloud popping accompanying the vin'- terruptionfof anoverload current oi high magni- 35'f ,tudv

n In carrying out my invention a satisfactory circuit )breaker shouldtheseadvantages.

`ln-one io'rm therefof,y `I provides. circuit breaker `which is capable-of tween' the separating contacts. the gas pressure f within thechamber Increases quite rapidly.' ^'l-his may bec! the lorder of 1000pounds per square inch. Theresistanceof thearc' increases :rapidly withpressure 'so that vas the pressurcis ot the springs are s ecured to.inwardly projectv ving ends 38 of the frame I3.' It will be observedthat the circuit represented by the conductors LIII 35 4 and I I may betraced fromh conductors I I through the branch 'circuit breaker byconductor I0, thermal' element Il; flexible conductor I2, movablecontact member 3I, 4 stationary v contact member 4t provided in the arcinterrupter or compres- 4o sion chamber I l and by conductor M tothe; 4-"conductor III.` Thcontact'members 3l and are' constructed oran arcresistant material, for

sistantmaterials may ofcourse be used.

The operating mechanismof 'the-branch circuit breaker is trip free; thatis to say, the operating handle; II, even though operated, cannotexample, in theoperation'oimy invention it -willbe 'observed' thatthefcircuitbreake is normally closed after Ait has opened in response`to ya ent, the parts then being in the relativepositions shown Fig. 1.,by 55 predetermined maximum' 4:I

example y,silver molybdenum, but other` arc rrcmaintain' a closedcircuit 1f ar current 'exists orf suilicient magnitude to' open the"breaker. For 5omoving the operating handle III to the right, whereby theoperating member I3 is rotated in a clockwise directionfaround its pivotI1 to bring its projection 2| into engagement with the notch 22 in thelinks 26 and thus move the links 26 a slight amount in a clockwisedirection and also bodily downwardly. When the handle I9 strikes the endof the frame 33 the movable 'parts are in the positions shown in Fig. 2.A projection 48 extending from the links 26 is moved from the positionshown in Fig. 1 downwardly beneath a latch4 49 carried by the thermalelement I4. The latch may of course be operated by means other than athermal element. Atthis time the movable contact 3| has not engagedthestationary contact 43 to close the circuit. As soon, however, as theoperating handle I9 is released the springs 31 rotate the links 26 aboutthe projection 48 to operate the movable contact 3l into engagement withthe contact'43 with a snap action, thus closing a circuit through thebreaker. The springs 31 expend only a part of their energy in operatingthe contact 3| to the closed position. The remaining energy isat alltimes available for operating with a snap action the contact 3| to theopen circuit positionA in response to overload or short circuitcurrent.y The. floating links 26. in the final or closed circuitposition are vfree of the operating handle. The links 26 as they freelthemselves from the handle I! impart to the handle through theprojection 2| an impulse which returns the handle towards thev oiposition. As shownl in Fig. 1, the handle is retained in an intermediateposition by the engagementA of the end 20 of the handle with the leafspring carriedon the frame. By moving the handle I9 'from ythisintermediate position vin a counterclockwise dlrectiomas viewed in Figs.1 and 2', a

projection |3a carried by the operating member I3 Voperatively engagesthe thermal element I4 to move it to release vthe latching projection48.

'I'he springs 31 thereupon operate the movable contact 3|- with,a snapaction to the open circuit position.

Assuming now that an overload occurs on the circuit represented by theconductors Il and II,

the thermal element I4 is ilexedin a clockwise `direction to release thelatching member 4 3 from the latching projection 43. vThe springs31$there upon cause the movable contact 3| to move toward the right asviewed in Fig. 1 with a snap action to the open circuit position shownin Fig. 1. As the movable contact 3l leaves the stationary contact 43,an arc is drawn between them. The arc interrupter I5 comprises a steelcylinder 53 within which a pair of kerosene-free ilber bushings 5I and52 extend. I have found that .kero.

sene-iree ber or an equivalent material is es. fsential to the operationof my invention and deem its use in the arc chamber an important part ofmy invention. The steel or metallic cylinde'rand the insulating membersare so arranged as to provide a sealed chamber of relatively smallvolume, such that the arc causes a rapid increase in air pressure in thechamber, the high air pres# sure exerting an-"opening force on themovable contact. This increase in pressure is due to the.

heating by the high temperature of the arc of the air within thechamber. The rise in pressure may be further accentuated by the heatingof other gaseous fluids produced by the action of the arc on Ithe airand the materials-within the In order to produce a strong and rigid'construction of thev arc chamber, the bushings gli and 52 are insertedinto the ends of the steel cylinder.

forming a. part of the conductor '44. The insulating bushing 5I permitsa reciprocal longitudinal movement of the movable contact member 3|,

one end of which is always locatedin the chamber and the other end ofwhich is always located outside of the chamber. 1

A leather sealing washer is provided around l5 the movable contactmember 3 I, the washer being provided with an inwardly projectingcylindrical extension 66. Since a certain amount of metal vapor isproduced when the Acircuit breaker ipterrupts a current of largemagnitude, it is neces- 20 sary to prevent this metal vapor fromcollecting on the movable contact member. 3| where it may harden andinterfere with successive operations of the circuit breaker. The leatherwasher with its inwardly iextending projection tends topre- 25 ventthis'collection of the metallic vapor because of its wiping action onthe movable contact mem.- ber 3| and furthermore assists in maintaininga substantially air-tight connection around the movable contact member`3| by its cooperation 80 with the contact member and the lwalls of thechamber. yAt the same timey the leather washer provides forsnap movementof the movableccn.- tact by the spring means by 'offering onlyrelatively slight friction to such movement. g5

I have stated, when aliA arc isdrawn between the contacts 3| and 4 3,the air pressure within .the chamber of the'arc interrupter in-` creasesrapidly. The'potential drop across the f proximately proportional to thein rse square i root of the current. This characteristic oi' thearc,-in, addition to the rise inpressure in the chamber, causes a quickinterruption ofthe circuit. Furthermore, since the rise in pressure' defpends upon the magnitude of the current inter' rupted, it will be seenthat the greater the'over- 4load current thel more quicklyl will thepressure rise to a point where the arc resistance.be comes so great thatthe arc can v.no longer Obviously, the pressure within the chamber alsoexerts an opening force on theV movable contact accelerating its speedof opening in proportion to the degree of pressure built up by the heatof the arc.

Of course, it will be understood that in order to reclose the circuitbreaker it is only. necessary to .Il

repeat the operations described in connectionl with Figs. 1 and 2.

Referring now to Figs. 3, 4', 5 and 6, I have shown what is believed atthe present time to be'V the'best form of an operating mechanism. ThisII particular operating mechanism forms no part of my present invention,and it is described and claimed in a copending application Serial No.667 ,855, riled April 25, 1933, Atwood, entitled Circuit breaker andassigned to the same assignee 76 as the present invention.

A base Il formedof molded insulation provides a. support for theoperating mechanism as wellasV for the arc interrupter I5. -Theuar'cinterrupter or compression chamber-I5 is within au15 enclosure u moldedintensity with 'me The stationary contact 4 3 is providedwith screwthreads 6I engaginga-'threaded aperturein l shaped conductor M, `therinner threaded end 'Il fofwhich is located within the molded enclosure:n.the other end of the conductor u' extending ythrough aslotllto form aterminal. 'Ille movy Y able contact member '3i is mounted for reciprocallongitudinai movement into and out oi.'- cngage 10` mentwiththelstationary'contact 4l'. kA wiisher f llof leather or other suitablematerialjisplaced y,between the bushing" II and aclosuremember Il Y-"jprovided with a ilange l1 arranged to'v enkele the notched end Il ofthe insulating enclosure Il.

at -'molded integrally with the encloaure'll.' The frame. .Il is securedby screws Il extending through the base l0 in a position suchthat the`rame, therefore. performs thedouble "function 'Y' f maintaining theclosure` in place and sup? the operating mechanism.

@ The reclprocal'vertical movementl ot con-'V member 3| is obtained ybymeans of a pair of f yover-center springs 08, which springs have theircorresponding upper ends I0 carried by .projections IIII secured onopposite sides of the operatinghandle IIII. The opposite ends of thesprings "98j are secured 'to a pin |02 extending through an aperture inthe movablecontact 3l near its outer end. The operating handle `IM issecured toan -f i'nvertcd U-shaped operating member Iiaswhich in turnhas its legs mounted on a pivotpin I 49 carried by the 'upper ends ofthe arms vof the ilshaped support 09. When the operating handle is movedfrom vits left-hand position, shown in Flg`. 3, to its right-handposition, shown in Fig. 4,

u the movable contact II is moved lto and from its [reciprocal verticalmovement ot the movable con;

osed circuit position with aI snap `action. The

taci; li isinsured by member I04a,comprising `r'two parallel legsconnectedy together' by a midportion 1Mb. The upper endsot the legsmounted on the pivot pin I, while their lower ends-are'pivotallysecuredto the pin IGZ.

vertical ydirection to ment-oi the pin I0 2 caseot overload, abimetallicthermal element /Ill which is iJ-shaped as shown in Flg.'6 and connectedin) circuit with the switch contacts soas to be heated bythe currentpassingthrough thebreaker. -is caused to iiex away irom a latch pivotpin lu. 'rm-, memberl la has s non m yinto` which extends a'rodfl I2into abutting relation with the member I Il. A compression' spring:engaging a stop memberfiltzsecured tothe extensions!! rof the framevll,\ vhile the other end is emma base Il.

The operating mechanism is supportedirom the I1 by means of aUfshapedifframe Il.' yExtend-- at right angles irom'the `upper ends'oithe,

portion Il. of the frame abuts the .closure member le and maintains itsecurely in place. .The

.Since the lower end` ot the member Illa lnovcsv in acurved path aboutthe pivot |04, the openingv yinthe movablecontact member II throughwhich 'thej pin It! extends is elongated in a vertical ydire'ction,i..e., inthe directions!v the'pivot pinA I Il, so that sui'iicient lostmotion is obtained in a provide for-freedom oi' move'- AvIll rto permita quick opening of the circuit. It4 [will be observed thatthe latch IlssuDDOrted by aftripping'member I II which is mounted on the I iiitfe'icircles the rodandhas one end normally u engagea memberIiisecured'to the ill.L The tripping' spring I'II is shown co as showninFig.'5. As soon as the thermal element IIII releases thetlatchingmember I", it will be observed that .the `torce exerted by thetrippingspring IIB is applied to the memberv III at [the notch III.Thisioroe urges the tripping A member-I I I in a clockwisedirectionaround its :splint Hl. l The end Ioi^the tripping member I'IIIengages the connection IMb ofthe member Illa which it be remembered 4islconnected to the movable contact 3|.. 'The spring IIU inKV rotating themember IIII in a clockwise direction thus quickly operates the contactII to itsjopen' circuit position as shown in Fig. 4.l A projection II'lafoi the tripping member III isl located lust below the extensionsIIIb end IOIc extending from the operating handle IBI'. An opening ISIis provided in 'the extension IOIc`. The relative movement of thetripping member IIII 'from the 20 positdon shown in'Fig.- 3 totheposition shown in Fig. 4 brings asuitably colored portion on theextension I IOa into registering relation with the opening III so thatan indication is givenl that the circuit bre tion.

been opened. by overload as Just described, the handle IIIr is firstmovedy in a counter-clockwise 1 extension .III formed integrally Awiththe operatingmember IIIIa strikes 'a projection I2on the tripping memberIIIv and :thereby rotates the tripping member in a counter-clockwisedirec-l position as shown iny Fig, 3. 'Ihe switch closing operation isvthen completed by operating the handle I 'in a clockwise direction tothe posi-l tion shown in Figf., A second projection' I21 iormsdon theoperating member IIIIa strikes the frame Il at the point indicated bythe reference numeral Ill and acts aa a stop forthe'operating member. YWhile I have shown a particular embodiment `oi' my invention, it willbe'understood, of course, that Ido not wish to belimited thereto sincemany modincations may be made, and I..there fore. contemplate by theappended claims* to cover-any such modiiications as fall within the truespirit and scope of my invention.

' What I claim-as new and 4desire to secure by Letters Patent ofthe'United States, lszf 1 Ain electric circuit breaker for interrupting.

currents ot 5,000 amperes at lighting circuitvolt'- bushing secured toeach forming therewith agas tight' circuit interrupting chamber, astationary contact member extendingv through one oi' said bushings intosaid chamber, a coacting movable contact member 60 guided for`reciprocal Ilongitudinal movement within the other of said-bushingsinto -andout of contact with said'stationary contact member,

a packing gland-includlnga fibrous member co:

actingwith Ssaid last named bush movable contact to seal saidinterrupting chamber around said movable contact member against theescapeoi' gas athlghpressures during circuit interruption, 'said chamberhaving a relatively small volume'such that the air entrapped atlatd'omospheric pressures in said chamber is heated by the arei formed uponseparation oi-said contact j members to generate high gas pressureson'the order of 1.000 pounds per squarerinch, whereby currents ot5.000'amperes at lighting circuit volt-' Y75 Vpressed lnFig. 33nd 5;with the contacts 010566. i

aker hasbeen tripped to its o pen posi' lili In order close the circuitbreaker after it has direction from the position shown in Fig. 4. An

non until the latch los is again' in' the latcned 3 5 v ages comprisinga metallic cylinder, an insulating 55 end oi' said cylinder and ing and,said 4 ages may be-interrupted without burning of .said contact members.

2. A circuit breaker for interrupting currents of 5,000 amperes or moreat lighting circuit voltages comprising walls of pressureresistantmaterial forming a gas tight compression chamber, a stationary contactand a movable contact in `said chamber. snap action operating means forsaid movable contact on the exterior of =said chamber, said wallsdefining a chamber having'a relatively small volume such thatthe airentrapped at atmospheric pressure in said chamber is heatedfby the arcformed upon separation of said contacts to generate high gas pressureson the order of 1,000 pounds per square inch, whereby said breaker iscapable of interrupting cur-i rents of 5,000 amperes at lighting circuitvoltages without detrimental burning of said contacts.

3. A circuit breaker for interrupting currents of 5,000 amperes atlighting circuitvoltages comprising a metallic cylinder, an insulatingbushing mounted in each end of said cylinder, an annularl ilange on eachend oi said cylinder ensgagingthe peripheryA of. the correspondingbushing, each of said flanges being swaged over the periphery of itsbushing to form gas tightseais between said cylinder and said bushingsand thereby forming with said cylinder a gas tight circuit. interruptingchamber, a stationary contact member ex Atending centrally through oneof said bushings into said chamber, a coacting movable contact membermounted in the other oi' said bushings for reciprocal .longitudinalmovement, vsaid. cylinder and said bushings defining a chamber having arelatively small volume such thatvthe air y,

entrapped at atmospheric pressure in said chamber is heated bythe arcformed upon separation of said contacts to generate high gas pressuresof 1,000 pounds per square inch or more, whereby said breaker is capableof interrupting currents oi 5,000 amperes or more at lighting circuitvoltages without detrimentalburning of said contact members.

'4. A circuit breaker for interrupting currents of 5,000 amperes or moreat lighting circuit voltages comprising a metallic cylinder, a bushingmade oi insulating material mounted at each end of said cylinder andforming therewith a circuit -interrupting chamber, a stationary contactmemmovable contact member mounted in the other of said bushings andguided thereby for longitudinal movement, said bushings havingrelatively narrow peripheral portions tightly engaging the end walls ofsaid lcylinder, sealing means between said movable contact member -andits guiding bushing -for substantially precluding the escape o! gas athigh pressure fromsaid chamber during circuit interruption; saidcylinder and said bush-v ings denning a chamber having arelatively'small volume such thatthe air entrapped yat 'atmos- -phericpressure in said chamber is heated by the arc formed-upon separation ofsaid contacts to generate high gas pressures of .1,000 pounds per squareinch or more, whereby said breaker is a capable of interruptingcurrents' of 5,000 amperes or more at lighting circuit voltagesv withoutdetrimental burning of said contact members.

ber mounted on one of said bushings, a coacting LUDWIG s. wams. as

